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Windows terminal tab freezes when ssh is disconnected within WSL #10183
Description
Windows Terminal version (or Windows build number)
10.0.19043.985, 1.7.1033.0
Other Software
Windows 10 21H1 (OS Build 19043.985)
Windows Terminal Version: 1.7.1033.0
Cygwin64
Cygwin mintty 3.4.2 (x86_64-pc-cygwin) [Windows 19043]
OpenSSH_8.4p1, OpenSSL 1.1.1f 31 Mar 2020
WSL
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017
Linux -T480 5.4.72-microsoft-standard-WSL2 #1 SMP Wed Oct 28 23:40:43 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Ubuntu Workstation
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017
tmux 3.2
Steps to reproduce
1 - VPN is connected to corporate network.
2 - Open Windows Terminal and start Ubuntu 18.04 WSL2
3 - SSH to remote machine within WSL2. I ssh to my Ubuntu 18.04 workstation in corporate network.
4 - Create a new tmux session session. tmux new -s test
5 - Disconnect VPN (Uncheck connect automatically)
At this step, terminal freeze should be reproduced, and it should not be responding to any keys, which is a bug 1. I have to close the terminal tab, and open another one to continue.
Expected Behavior
1- When VPN is disconnected, and ssh should be disconnected within the terminal as Cygwin does. However, Windows terminal gets stuck though.
Actual Behavior
1 - Windows Terminal has a blinking cursor, however; it doesn't response to any key ctrl+c or any other keys.
2 - It doesn't seem to try disconnects after connection timeout. Terminal hangs. The only way is to close the terminal tab.
Activity
DHowett commentedon May 25, 2021
Thanks for filing this! Terminal doesn't actually control what happens here -- its job is to get characters out of SSH on to the screen, and from your keyboard back into SSH... or whatever application is connected. How a process handles the socket dropping, or SIGINT (from Ctrl+C), or user input is up to that process, at the end of the day.
When you get it into this state, if you press the following:
ENTER ~ .
what happens?
ismailhkose commentedon May 26, 2021
I get the following message.
Connection to <IP> closed.DHowett commentedon May 26, 2021
It looks like Terminal is still passing input to the SSH process, as the SSH "session break" key combo continues to work. 😄
At the end of the day... if an application inside Terminal isn't responding normally it's much more likely to be the application's fault rather than Terminal's. You'd probably observe the same behavior if you used wsl inside the console host.
There's a chance, of course, that it's a WSL issue. Given though that it's WSL2, that's also unlikely. Sometimes SSH just thinks it's still connected.
ismailhkose commentedon Jun 1, 2021
I don't get this error when I use Cygwin as a terminal. Please see the openssh and terminal versions in the first message. Any idea?
DHowett commentedon Jun 1, 2021
The Cygwin runtime handles the "link disappeared while we were using it" state better than what you're seeing in WSL. This is probably because the Cygwin runtime is using Windows sockets natively, whereas WSL is running in a hypervisor with some network forwarding and stuff so it's missing the connection drop event.
If you run WSL outside of Windows Terminal, it's going to behave the same way.
ismailhkose commentedon Jun 15, 2021
So, where should I file this bug to?
ismailhkose commentedon Jun 15, 2021
I created a networking related issue in WSL, but I am not sure how relevant it is.
microsoft/WSL#7030
Petros626 commentedon Sep 19, 2024
I did the following, which worked for me (Windows 10 & WSL2):
sudo nano /etc/ssh/ssh_configsudo nano /etc/ssh/sshd_configservice ssh restartssh nameofmachine@xxx.xxx.xxx.xxnishaalnaseer commentedon Nov 18, 2024
Putting the PC to sleeps breaks SSH connection and i cant get the terminal tab to work again.
Steps to reproduce:
ENTER ~ . doesnt work.
The connection automatically closes but its taking too long. I think this takes around 15 minutes
Using ctrl D on responsive connection works but not on an unresponsive connection.
Im not on WSL, just windows preview build on terminal
Any tips to fix? should i create a new issue?
I personally think a way to force restart a tab no matter the circumstances would be good. Right now i can close a tab... but doing so would make me lose any split tabs i have open.